1. Field of the Invention
The present disclosure relates generally to the fabrication of integrated devices, and more particularly, to the detection of particles on substrates used in the fabrication of integrated devices.
2. Description of the Related Art
Particulate contaminants are undesirable in the fabrication of integrated devices. As feature sizes continue to shrink, particulate contamination becomes increasingly troublesome. A single particulate contaminant in the wrong place can create a “killing defect,” rendering an entire integrated device non-functional. In addition to the location of the particle, its composition can make it more or less troublesome. Certain types of particles are more problematic than other types, depending on the process. For example, copper diffuses through oxides and silicon. Copper is soluble in silicon at processing temperatures and diffuses throughout the bulk silicon very rapidly. On cooling, the copper precipitates as copper silicide (Cu3Si) on the surface of the wafer, damaging the wafer and thereby reducing the yield. Because of copper's high diffusivity, even particulate contamination on the backside of the wafer can damage the frontside of the wafer. Nickel, iron, and other metallic contaminants present similar problems, but to a lesser extent.
Consequently, it is important to accurately detect particles in the manufacture of integrated devices. It is also important to determine the compositions of the particles.